ZATSUYOSEN!

15 November 1931:
Nagasaki. Laid down by Mitsubishi Zosen K.K. Nagasaki Zosensho shipyard as the last of six diesel-driven high speed cargo ship, for Osaka Shosen K.K., Osaka. HOKKAI and NANKAI MARUs are improved versions of 1930 built KINAI MARU and her three sisters. As opposed to KINAI MARU’s Swiss made Sulzer engines, HOKKAI MARU is powered by Mitsubishi MS-type diesels that give better performance with less fuel oil consumption.

30 October 1938:
Placed on European Lines: Kobe ~ New York. One round cruise usually takes five months.

E 1940:
Her net registered tonnage is changed for 5,105-tons.

5 April 1941:
Starts her sixth voyage on European Lines: Kobe ~ New York ~ Europe.

July 1941:
In retaliation to Japan’s occupation of French Indochina, the United States closes the Panama Canal to Japanese shipping.

23 September 1941:
Requisitioned by the IJN as a transport (Ippan Choyosen). [2]

2 October 1941:
Yokohama. Starts conversion to her military role in Mitsubishi Heavy Industries K.K. shipyard.

10 November 1941:
Registered in the IJN as an auxiliary transport under internal order No. 1391 and attached to the Yokosuka Naval District as an auxiliary transport, (Ko) category. Her home port is Yokosuka. [3]

13 December 1941: Operation "B" - The Invasion of British Borneo (Sarawak):
The occupation of British Borneo is a combined IJN/IJA operation which involves Gen (later Field Marshal) Count Terauchi Hisachi’s command’s Southern Expeditionary Army. The 25th Army, under LtGen Yamashita Tomoyuki fields MajGen Kawaguchi Kiyotake’s “Detachment” of about 2,500 men consisting of the 35th Infantry Brigade HQ, the 124th Infantry Regiment led by Col Oka Akinosuke, 18th Signal Unit platoon, 18th Medical Unit and 18/4 Field Hospital Medical Unit. In addition, five specialized and supply units are embarked on the transports: 21st Field Ordnance Depot Coy and 1st, 2nd, 3rd & 4th Field Well drilling Coys of about 120 men each (oil well repairs if needed). Finally, one AA and one Signal Regiment are stationed on IJA transports.

14 December 1941:
The Invasion Convoy crosses the South China Sea without being sighted. MITAKESAN MARU is detached to the Philippines.

15 December 1941:
At 2330, the main body of the convoy arrives at Miri anchorage. At midnight, HIYOSHI MARU arrives at Seria anchorage. About the same time, all IJN transports arrive at Lutong. Because of a rainstorm, three
Daihatsu barges capsize when lowered into the water. 19 IJA landing troops are KIA and 15 are MIA.

16 December 1941:
At 0440, troops land at Miri, Seria and Lutong. Despite worsening weather conditions, landings are made without opposition from British defending units and Miri, Seria and Lutong oilfields as well as Miri airfield are all secured in the morning.

17 December 1941:
N of Miri, near Seria. Destroyer SHINONOME is attacked by Dutch Dornier Do-24 K-1 flying-boat X-32 of Aircraft Group GVT-7 based at Tarakan, E Borneo. Of five 200-kg bombs she drops, the X-32 scores two direct hits and a near-miss. An explosion severs SHINONOME's stern and she sinks quickly with all hands - the first FUBUKI-class destroyer sunk in WWII.
A Do-24 X-34 flying boat of GVT-7 attacks a vessel, but is intercepted by a Type O Mitsubishi F1M2 ‘Pete’ from KAMIKAWA MARU. The Dornier is forced to make an emergency landing with two of its crew dead. Two hours later, in bad weather conditions, six Dutch Glenn Martin bombers of 2-VIG-I also attack. A Pete from KAMIKAWA MARU attacks the Dutch bomber formation, but they escape. [4]

19 December 1941:
Miri. In the morning, Martin B-10 medium bombers from 1-VIG-I and 2-VIG-I based at Samarinda and Singkawang attack the invasion shipping. Four KAMIKAWA MARU’s F1M2 “Pete” floatplanes intercept separate trios of bombers that appear at 15-minute intervals. The Petes’ pilots claim downing Martin M-571 of 2-VIG-I.

20 December 1941:
Miri. About midday, six Martins of 2-VIG-I escorted by two obsolete Brewster “Buffalo” fighters attack Japanese shipping off Miri. The bomber crews miss a cruiser. F1M2s from KAMIKAWA MARU intercept
and claim one bomber. The Buffaloes escape with heavy damage.
That same day, an E13A1 Jake from KAMIKAWA MARU fails to return from a reconnaissance mission.

23 December 1941:
Early morning, about 150 miles from Kuching, a Dutch reconnaissance aircraft spots the Invasion Convoy.
At 11.40 that morning twenty-four Japanese aircraft bomb Singkawang II airfield, so damaging the runways that a Dutch striking force which had been ordered to attack the convoy is unable to take off with a bomb load.
At 1800, the convoy approaches the mouth of the Santubong river. Subsequent landings are made again with little opposition from British Forces although four Daihatsu landing craft are sunk. Moreover, both convoy and escorts do not escape unscathed.

Off Kuching. At 2040, Dutch Ltz I Carel A. J. van Well Groeneveld's submarine K-XIV attacks the anchored transports. He torpedoes and sinks in sequence IJA transport HIYOSHI MARU with five crewmen KIA, and IJN transport
KATORI MARU with the loss of 10 crewmen and many troops. IJN transports HOKKAI MARU and TONAN MARU No. 3 are also damaged by K-XIV’s torpedoes. HOKKAI MARU is heavily damaged and beached to prevent her sinking. [5]

28 May 1944:
At 0800, departs Balikpapan for Palembang, Sumatra in convoy also consisting of tanker NIPPO MARU escorted by patrol boat PB-2. At 2137, arrives at Kotabaru, Laut Island.

29 May 1944:
At 0755, departs Kotabaru.

30 May 1944:
HOKKAI MARU suffers steering problems and a long delay is experienced. Arrives at Palembang and is detached from the convoy.

2 June 1944:
Departs Palembang for Bintang.

3 June 1944:
Arrives at Bintang.

5 June 1944:
Departs Bintang.

7 June 1944:
Arrives at Singapore.

17 June 1944:
At 0400, departs Singapore for Moji in fast convoy HI-66 also consisting of tanker OMUROSAN MARU and transports/cargo SANUKI and AWA MARUs escorted by escort carrier KAIYO, light cruiser KASHII and kaibokan
CHIBURI, CD-7 and CD-11. The convoy hugs the continental coast avoiding deep water as much as possible.

15 August 1944:
HI-71 arrives at Mako, Pescadores. NIYO, HAKKO No. 2 and ORYOKU MARUs and IRAKO are detached from the convoy. NIYO MARU is later reallocated to convoy.

17 August 1944:
HI-71 sorties from Mako for Manila in Typhoon weather transporting troops and supplies for the defense of the Philippines. Kajioka's escort forces are augmented by old destroyer ASAKAZE and kaibokan SADO, ETOROFU, MATSUWA and HIBURI sent from Takao by the 1st Surface Escort Division. After two hours out, NIYO MARU suffers an engine breakdown and returns to Mako.

Off Cape Bolinao, Luzon. At 2222, LtCdr (later Captain) Henry G. Munson's (USNA ’32) USS RASHER (SS-269) attacks carrier TAIYO, bringing up the rear of the convoy. TAIYO is hit by three torpedoes and sinks quickly. 747 crewmen and passengers are KIA. At 2310, RASHER, still on the surface, hits transport TEIA MARU with three torpedoes using radar bearings. The ex-French liner is set afire and sinks, taking with her 2316 troops, 275 other passengers and 74 crewmen and gunners.

19 August 1944:
The convoy splits into two groups. Just past midnight, USS RASHER, still running on the surface, closes on an eastbound group of three large ships and one escort. At 0033, LtCdr Munson puts two radar-directed torpedoes into the port sides of AWA and NOSHIRO MARUs at 18-11N, 119-58E. Both ships beach themselves near Port Currimao.
LtCdr (later Cdr) Charles M. Henderson's (USNA ’34) USS BLUEFISH (SS-222) and LtCdr (later Captain) Gordon W. Underwood's (USNA ’32) SPADEFISH (SS-411), on her first patrol, join in the attack on HI-71. At 0320, USS BLUEFISH hits HAYASUI. Set afire, she sinks by the stern. Underwood's USS SPADEFISH hits TAMATSU MARU with two torpedoes and the big landing craft depot ship rolls over and takes down 4,755 troops and 135 crewmen.
At 0420, Henderson’s USS BLUEFISH hits oiler TEIYO MARU. She is set afire an abandoned by her crew. At 0510 Henderson attacks again the crippled ship and finishes her off. She sinks by the stern with the loss of 99 crewmen and passengers.

Admiral Kajioka orders HI-71 to make for San Fernando. SADO, MATSUWA and HIBURI are ordered to cover the convoy's flight with antisubmarine sweeps.

21 August 1944:
Under tow, AWA MARU arrives in Manila after the main body of the convoy arrives.

25 August 1944:
At 1650, departs Manila for Singapore in convoy HI-71 from now also consisting of oilers AZUSA, KYOKUTO, KYOKUHO and ZUIHO MARUs, and transport AWA MARU escorted by destroyer FUJINAMI, kaibokan HIRADO, MIKURA and KURAHASHI and subchaser CH-28. At 1845, KYOKUHO MARU develops engine trouble and drops behind escorted by FUJINAMI. Later, they catch up with the convoy but are finally detached for Miri.

15 August 1945:
Still under repairs at the termination of hostilities, due more than likely to an acute shortage of materials.

2 October 1945:
Seized by the Indonesian People’s Front. All crewmembers are taken to a concentration camp. Seven die in captivity.

12 November 1945: A fire breaks out of her engine room. Despite firefighting work from a British patrol boat, HOKKAI MARU is engulfed in flames and settles on the seabed.

Authors Notes: [1] Not to be confused with Dairen Kisen’s (2278 GRT ’40), IJA small repair ship (457 GRT, ’42) and auxiliary IJN supply ship (407 GRT, ’34).
[2] See Zatsuyosen home page for full explanation.
[3] There were two categories of Zatsuyosen. (Ko) category with an IJN Captain as supervisor aboard and (Otsu) category without.
[4] The survivors float in their dinghy for three weeks, finally getting ashore 260 miles to the south, where they become POWs. In 1945, shortly before the Japanese capitulation, the crew is executed.
[5] One source indicates that TONAN MARU No. 3 made Saigon a few days later for temporary repairs.
[6] Sources are conflicting whether mines were Mk 12 Type laid by LtCdr (later Rear Admiral-Ret) Walter T. Griffith’s (USNA ’34) USS BOWFIN (SS-287) in Jan ’44 or aerial mines dropped by a B-24 aircraft.